mongodb索引操作

查看索引情况

db.imooc_collection.getIndexes()

> show tables

> db.imooc_collection.getIndexes()[ ]

> db.imooc_collection.insert({x:1})

WriteResult({"nInserted":1})

> db.imooc_collection.find()

{"_id": ObjectId("586df1ba46208ecdd6d08b36"),"x":1}

> db.imooc_collection.getIndexes()

[{"v":2,"key": {"_id":1},"name":"_id_","ns":"imooc.imooc_collection"}]

创建索引

db.imooc_collection.ensureIndex({x:1})

> db.imooc_collection.ensureIndex({x:1}){"createdCollectionAutomatically":false,"numIndexesBefore":1,"numIndexesAfter":2,"ok":1}>

索引可以重复创建，对于已经创建的索引会直接返回成功

> db.imooc_2.getIndexes()

[{"v":2,"key": {"_id":1},"name":"_id_","ns":"imooc.imooc_2"},{"v":2,"key": {"x":1},"name":"x_1","ns":"imooc.imooc_2"}]

> db.imooc_2.ensureIndex({x:1}){"createdCollectionAutomatically":false,"numIndexesBefore":2,"numIndexesAfter":2,"note":"all indexes already exist","ok":1}

> db.imooc_2.find()

{"_id": ObjectId("586df44f46208ecdd6d08b37"),"x":1}

创建复合索引

> db.imooc_2.ensureIndex({x:1,y:1}){"createdCollectionAutomatically":false,"numIndexesBefore":2,"numIndexesAfter":3,"ok":1}

创建过期索引

> db.imooc_2.ensureIndex({time:1},{expireAfterSeconds:30}){"createdCollectionAutomatically":false,"numIndexesBefore":3,"numIndexesAfter":4,"ok":1}